Fitness Drives Natural Selection by Shaping Survival and Reproduction
- Imagine a pride of lions competing for limited water during a drought.
- Only those with the strongest adaptations such as endurance or keen senses will survive to reproduce.
- Over time, these traits become more common in the population.
- This demonstrates the concept of fitness, and is natural selection in action.
Definition
Fitness
Fitness refers to how well an organism is adapted to its environment, influencing its ability to survive and reproduce.
Variation Provides the Raw Material for Natural Selection
- Populations exhibit variation in traits, which is essential for natural selection to occur.
- Key Sources of Variation:
- Mutation: Introduces new alleles.
- Sexual Reproduction: Shuffles alleles into new combinations through meiosis and fertilization.
Intraspecific Competition Creates a Struggle for Resources
- Individuals within a population compete for limited resources, driving natural selection.
- Competition: Intraspecific competition occurs for food, water, mates, and space.
- Selection Pressure: Traits that improve access to resources increase an individual’s fitness.
